DJ, there's really no need to try any further adjustments. If the volume control has no effect whatever, it's clearly inoperative. To clarify what it actually does, note that audio amplifiers have a fixed non-adjustable gain(typically increasing the incoming voltage about 30 times)and the control is a variable resistor which varies the amount of the voltage let in to be amplified from nearly 100% to almost zero. Obviously the control on your EP500 isn't doing this and appears to be letting in the full voltage from the sub pre-out. The amplifier itself is probably fine since it's driving the sub too loudly, but the volume control needs repair or replacement if possible. Contact Axiom.

I am having a similar problem with an EP600 of the same vintage. The difference is that I have almost NO output. Gain control on both the sub and receiver is maxed out. Green light is on. Sub amp is warm. Tried using my iPod as a source, but no change. Both fuses are fine. Checked the internal wiring connections at both driver and amp. I'm stumped. It doesn't sound fried. In fact, the sound quality is fine. It's just that the volume control on the amp has two modes - off, and very low. Anything I've missed? (Sorry for the hijack)

Shawn, really nothing to suggest, other than saying that the volume control(again, not a "gain" control)on your EP600 appears to be "stuck" near the minimum, while DJ's is near the maximum. If you haven't run it rapidly up and down a couple dozen times, you might try that to see if it breaks something loose.

Well, it's definitely not the driver. Hooked up the amp out of an old AX500 sub. Lots of output. Relatively - it's only rated at 165 watts. I immediately disconnected it after the test. The last thing I need is my kids frying the voice coil by clipping that tiny amp!!I have a call into Brent. Just waiting on a response.

Update - Sub is out of warranty. There have been significant changes to the amp design over the last 6 years, that Axiom does not have the ability to repair the old one. I'll have to purchase the current version. Brent was kind enough to offer a discount off retail, though. Thanks Brent!

Interestingly, the new amp has individual output stages for EACH of the two voice coils.